Method for determining the depth of immersion of electrodes in a reduction furnace

ABSTRACT

A method of determining the immersion depth of electrodes in a reduction furnace which includes measuring the voltage distribution occurring on the furnace wall produced by the currents induced therein. These currents are induced by the magnetic field developed in response to furnace currents flowing from the electrodes during operation of the furnace.

United States Patent [1 1 Thomas 1 July 31, 1973 METHOD FOR DETERMINING THE DEPTH [56] References Cited gggg g ig gg g fi A UNITED STATES PATENTS v 3,622,678 11/1971 Allen 13/9 ES [7 51 Inventor: Johann Thomas, Erlangen, Germany. 3,209,060 9/1965 Borrebach 13/13 [7 3] Assignee: Siemens Aktiengesellschaft, Berlin and Munich, Germany Primary Examiner-Roy N. Envall, Jr. Attorney- Arthur E. Wilfond, Herbert L. Lerner et al. [22] Filed: Jan. 18, 1972 [21] Appl. No.: 218,766 57 ABSTRACT i A method of determining the immersion depth of elec- [30] Forelgn Apphcafio Pnomy trodes in a reduction furnace which includes measuring Jan. 25, 1971 Germany P 21 03 216.6 the voltage distribution occurring on the furnace wall produced by the currents induced therein. These cur- [52] US. Cl. 13/13, 13/34 rents are induced by the magnetic field developed in [51] Int. Cl. l-l05b 7/12 response to furnace currents flowing from the elec- [58] Field of Search 13/9 ES, 9, l2, l3, trodes during operation of the furnace.

3 Claims, 4 Drawing Figures u v w 11 nace by measuring the distribution of the magnetic I fields produced by the furnace currents.

In reduction furnace, there exist magnetic fields which are developed by the horizontal current flow in the reaction zone of the furnace. According to a knownmethod, theseelectromagnetic fields are used as an. indicator for determining the depth ofimmersionof the electrodes. The current travelling horizontally in the" reaction zone produces vertically extending components of induction, while the currents runningvertically in the electrodes develop horizontal components of magnetic induction. The maximum of the vertical induction field is located at the elevation of the maximum horizontal current jump-over between the electrodes, that is, at the location of the reaction zone.

According to the known method, the maximum of the vertical induction field is determined by.-means of a magnetic probe movable up and down vertically on the furnace wall. However, the measuring result does not provide a reliable determination of the positionof the maxim um, because currents produced by the alternating induction fields of the furnace currents in the furnace wall and the steel building structure and because the field produced. by the horizontal currents in the furnace and located outside the ironfumace wall encounters difficulty because of high temperatureand the security of the furnace masonry;

Because of the requirementsof heat. technology and economics, it is important tomaintain the position of the reaction center of the reduction furnace constantat the same elevation, this position being dependent upon the depth of immersion of the electrodes.

Accordingly, it is an object of the invention to provide a method of determining the position of the reaction center with electrical measurements.

According to a feature of the invention, the position of the reaction center is determined by detecting the currents produced by the magnetic fields in the furnace wall; these currents are detected by measuring the potential distribution occurring on the oven jacket. In this connection, the potential differences arisingat several pairs of measuring points distributed across the furnace wall are measured and indicated. Preferably, these potential differences are directed to a process computer. With the aid of a device for controlling the electrode position, the process computer adjusts the potential difference at the pairs of measuring points to those values which correspond to the required immersion depth of the electrodes.

Although the invention is illustrated and described herein as a method for determining the depth of immer sion of electrodes in a reduction furnace, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein within the scope and the range of the claims. The invention, however, together with additional'objects and advantages will be best understood from the following description and in connection with the" accompanying drawings in which:

FIG. 1 illustrates in schematic representation a reduction furnace with electrode rods extending therein whcih is typical of the furnace used in carrying out the method of the invention;

FIG. 2 illustrates schematically a projection of the wall of the furnace of FIG. 1 showing the current formation therein; v

FIG. 3 illustrates the furnace of FIG. 1 connected to an electrical apparatus for carrying out the method of the invention; and, Y

- arcing furnace or resistance furnace comprises a conical furnace' shellconsisting of a steel furnace wall 1 and 1:5,

FIG. 4 illustrates the measuring of vertically distributed potential as well as an apparatus for adjusting the elevation of the electrodes.

Referring to FIG. 1 a reduction furnace such as an a heat insulating masonry portion 2. Also shown'as part of the furnace are three electrodes 3 connected to a three-phase current network indicated by the letters U, V, W. The reaction products or burden4 are placed in the furnace shell'and are melted and brought into reaction by a light arc and/or resistance heating. The liquid reaction product is drawn off through a tap port 5 in the side of the furnace shell. I 1

The current paths in the furnace are indicated by dashed lines in FIG. 1. The magnetic alternating fields generated by this current distribution induces in the furnace wall currents whose approximate formation is sketchedin FIG. 2 on the planar projectionof the furnacewall'. Since the magnetic fields are rotating fields, this current formation moves with the circuit frequency W along: the furnace wall'..As FIG. 2 shows, there are locations in'the furnace at which the current is atnull, whereas below and above these nulllocations, the current run in respective opposite directions. The position of thenull-locations6is dependent upon the depth'of immersion of the electrodes. I I

As illustrated in FIGS. 3' and 4' contact membersare welded to the outer surface of the fumace'wall: The mutual spacing of the contact mebers in horizontal directioncan equal*up=to'half the furnace periphery; On each two of the contact members a, a to d, d" and/or e, e' and f, f, a measuring device 8 or a computer 10 is connected via a twisted measuring leads 7 and a switch device 9 having a number of switches corresponding to the pairs of measuring locations. The measuring device 8 indicates thevoltages on the measuring points proportional to the alternating currents in the tor means in the computer 10 compares'the measured values to reference values that correspond to the correct position of the electrodes and the computer 10 sends a signal to the electrode control apparatus 11 which in turn adjusts the elevation of electrodes 3 until the voltage at the measuring point pairs corresponds to the values thereof co'rrespondingto the correct position of the reaction center.

I claim: i

1. A method of determining the immersion depth of electrodes in a reductionfumace in which the electrodes are supplied with electric energy during furnace operation comprising'the steps of causing furnace currents to flow from said electrodes, causing magnetic fields to be set up in the wall of said furnace as a result of said furnace currents, inducing currents in said furnace wall as a result of said magnetic fields, measuring at various points in the furnace wall the voltage caused by said induced currents in said furnace wall and utilizing said measured voltage values to control the immersion depth of said electrodes.

2. The method of claim 1, comprising th steps of measuring the potential differences at a plurality of pairs of measuring points on the furnace wall and,-indi- 

1. A method of determining the immersion depth of electrodes in a reduction furnace in which the electrodes are supplied with electric energy during furnace operation comprising the steps of causing furnace currents to flow from said electrodes, causing magnetic fields to be set up in the wall of said furnace as a result of said furnace currents, inducing currents in said furnace wall as a result of said magnetic fields, measuring at various points in the furnace wall the voltage caused by said induced currents in said furnace wall and utilizing said measured voltage values to control the immersion depth of said electrodes.
 2. The method of claim 1, comprising th steps of measuring the potential differences at a plurality of pairs of measuring points on the furnace wall and, indicating the potential differences on a measuring device connected to said pairs of measuring points.
 3. The method of claim 2, comprising transmitting the meausred potential differences to a computer, and adjusting the elevation of the electrodes with an electrode adjusting the elevation of the electrodes with an electrode adjusting apparatus in response to signals from the computer, the elevation of the electrodes being adjusted for controlling the potential differences at said plurality of pairs of measuring points to values corresponding to the required immersion depth of the electrodes. 